Chief Medical Officer Dr. Merlene Fredericks James ordered the ship quarantined after consulting with the Pan American Health Organization.

“We thought it prudent we quarantine this ship. No one was allowed to leave this ship,” James said.

James warned residents of the regional measles threat in the U.S., telling citizens of the island to vaccinate themselves and their children. There have been a record 704 cases of measles reported in the U.S. from January to April of this year.

“One infected person can easily infect others through coughing, sneezing … So because of the risk of potential infection, not just from the confirmed measles case, but from other persons who may be on the boat at the time, we thought it prudent to make a decision not to allow anyone to disembark,” Andrews said.

The vessel is still moored on the island, St. Lucia Coast Guard Sgt. Victor Theodore told NBC News.

The ship has been quarantined since April 30.

The luxurious 440-foot cruise ship has served as a retreat for the Church or Scientology since 1988 and is hailed as a ”an aesthetic, distraction-free environment off the crossroads of everyday life.”

According to the New York Times, John Carmichael, president of the Church of Scientology in New York, said in 2006 that the church had not taken a stance on vaccinations “as a religious principle.”

This trip, the first of two President Donald Trump is expected to make to Japan in the next six weeks, is more of a social call meant to highlight the alliance between Japan and the United States and the friendship between their leaders.